A harmful gas may be produced in a special space such as a scene of fire or a confined underground workspace. A worker may recognize a colored and odorous gas, but not a colorless and odorless gas. When the worker is exposed to an environment with a harmful gas for a predetermined time, an emergency may occur. For example, in a case in which a worker works in an underground environment where a concentration of carbon monoxide is greater than or equal to a predetermined level, it may harm a heath of the worker. If it is possible to detect a harmful gas and determine a degree of danger using a device carried by the worker, the worker may be protected from a harmful environment.
Korean Patent Publication No. 10-1663572 (published on Sep. 30, 2016) discloses a monitoring system of working environment for ensuring safety of workers. The publication discloses an environment monitoring module including a sensor unit that includes an oxygen sensor to detect a preset gas and measure a concentration of oxygen in the air when power is supplied thereto, a control unit to control an operation of the sensor unit, and a communication unit electrically connected to the control unit and connected to a smart phone of a worker through wired and wireless communication, and an application installed on the smart phone to determine a dangerous situation by receiving a detection value of the sensor unit through the communication unit and perform a warning signal in response to the determination of the dangerous situation.